Environmental Engineering Reference
In-Depth Information
Even the great drought in Eastern Australia in the 1890s only slowed their progress. With the pas-
tures gone, they swarmed in the cool of the night, reputedly piling up at fences until there were enough
bodies for the next wave to climb over and keep going. By 1950, despite a thriving trade in tinned rabbit
meat and rabbit skins, there were half a billion of them when the government introduced a new ali-
en, a Brazilian rabbit disease called myxomatosis, which killed all but a few thousand. The survivors,
however, have become the basis for a population revival.
Rabbits were blamed for turning rangelands to deserts, and they took the rap for a multitude of other
crimes, like taking over the holes of kangaroo rats, leaving them defenseless against foxes. But while
the tale of the rabbit is almost a defining myth of the new human nation, it is largely scapegoating. The
real damage had already been done by the farmers and their sheep. “In Australia,” says Mark Davis of
Macalester College, “declines in the native species typically began decades before introductions of spe-
cies . . . that have been reported to have contributed to the extinctions.”
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By trying to turn Australian
grasslands into European sheep farms, the colonists had “built a rabbit paradise,” says environmental
historian John McNeill. In the end, the rabbits couldn't fail. They simply occupied the ecological space
created for them.
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Humanity's involvement in moving species round the world is as long as our own migrations. Tribes of
Homo sapiens
left Africa for the Middle East 125,000 years ago, before the last ice age. They went to
South Asia 50,000 years ago; to Europe and Australasia 40,000 years ago; and to the Americas perhaps
12,000 years ago. We took species for company and food, to clothe our bodies and ornament our gar-
dens, for construction and manufacture, to hunt and fight pests, for zoos and as pets.
Many species have been eager to share our journey. We took with us, either deliberately or accident-
ally, many of the same companions we have today: dogs and cats, rats and mice, earthworms and bees,
sheep and goats, starlings and pigeons, wheat and barley, bananas and beans. They have been central to
our conquest of the planet. Before we invented agriculture, only a few million humans lived on Earth.
But domesticating and transporting species of plants and animals allowed us to feed many more. Today
seven billion of us are fed each day, mostly from plants grown very far from where they originated.
The wild varieties of wheat grew in the Middle East, maize in Central America, potatoes in the Per-
uvian Andes, soy in China, and rice in Southeast Asia. Polynesians sailed the Pacific with pigs, sweet
potato, breadfruit, and taro—and took chickens to Chile about a hundred years before Columbus began
the European species translocations.
Those trans-Atlantic migrations, dubbed the “Columbian exchange” by environmental historian Al-
fred Crosby, have always been two-way traffic. Wheat went to the Americas and potatoes and chocolate
came east to Europe. African slaves took rice with them to the Americas, while the British extracted
rubber, cinchona (to fight malaria), and peanuts from the Amazon jungles. There were other global jour-
neys. Acacia trees first arrived in Australia with Pacific traders, having originated in the Americas. They
then spread on colonial whims across the world, including to South Africa, where some of the largest
plantations were established.
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We can sometimes forget how much of our everyday landscape is foreign. Travel around the Medi-
terranean and you may imagine that the landscape is composed mostly of native crops. But the citrus
trees were brought by Arab traders from the Far East; the cypresses are from Iran; and the tomatoes,
tobacco, cactus, chili peppers, and much else came from the Americas. Cattle crossed into Spain from
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